Exposure Problems

akfotog · Feb 8, 2013

I also posted this in the B&W film section. OK, so I put my Hasselblad 500 C/M, 120mm f4 lens, and #32 ext. tube on my copy stand today to run my first roll of film through it since I bought it. The camera itself is in mint condition, as are the lenses and accessories. I first photographed a coin (see below) based on the readings from my Minolta IVF meter, which gave me a reading of 1.5 sec. @f22. No adjustments for light falloff using Fuji Acros 100 film. The results are fairly acceptable. Later I took another photo, this time of an old Kodak Pony (see below) back light, same basic setup, using the same meter readings. The camera is totally black, with no detail whatsoever. I know the meter is OK, as I also use it for my RB67 Pro SD and 4x5s. Any ideas? The back light shouldn't affect the exposure since it was read from my meter and not the camera, right? Any insight would be appreciated.

akfotog · Feb 8, 2013

Forgot to mention, I did take the #32 ext. tub off for the Kodak Pony photo.

Bill Burk · Feb 8, 2013

First off, akfotog, I gotta say I love your work...

Is the negative really bad? Or are you just not getting detail that really is there?

If the negative is thin, I think you might have allowed the backlight to influence the meter reading when you gotta know you needed to ignore it and find a way to measure the light hitting the front of the Pony.

Did you take the two lights from the front and move them to the back? Or are they still there on the front? If the lights in the front didn't move then you would use 1.5 sec at f/22 still.

A gray card is a great way to do copy work. And there are plenty of folks here who know how to use meters that can troubleshoot your metering technique and offer helpful suggestions.

henry finley · Feb 8, 2013

I think you are photographing things that really need a light tent, or facsimile thereof.

akfotog · Feb 8, 2013

Thanks Bill, and your work also is great. No, the meter was laid flat on the copy stand facing the camera, so only the lighting entering the camera should have been registered. The camera itself is silver, almost the same as the coin (a little brighter), so I should have gotten something out of it. I did both a 1.5 sec. and 2 sec. exposure, which bared nothing. Negatives for all 6 photos taken with the ext. tube on are OK, the next six, without, are all the same. You're right, I could have tried using the reflective side of the meter, as opposed to the incident (may have been better in this situation). (empty). Will shoot another roll tomorrow using the reflective meter and see what I get. Nothing like a little experimentation. Thanks again my friend.

akfotog · Feb 8, 2013

Never thought of that Henry,but still can't understand the vast difference while using the same exposure readings.

Bill Burk · Feb 8, 2013

Incident meter should have worked fine. Are you sure the negs are terribly clear? Backlighting should have left the background bleached white but what you showed doesn't go pure white.

akfotog · Feb 8, 2013

That was my intent Bill, kind of like photographing a model with a softbox behind, but as it turns out... No worries,nothing like playing around to get that almost perfect photograph. Thanks again for the tips.

akfotog · Feb 8, 2013

To clarify Desertratt, the coin was photographed on a black foam core background, and the Kodak Pony was photographed with back lighting. I used the same side lighting in both cases, which could probably looks like the lighting was moved. The Kodak Pony is silver (chrome) in color, brighter, but not that much different from the shading of the coin. Nothing changed between the two, other than the use of the extension tube in the coin photo, and the removal of the extension tube in the Kodak Pony photo with back lighting.

MattKing · Feb 8, 2013

What aperture or shutter speed adjustment did you use to take into account the fact that one set of photos involved an extension tube?

The photo of the Kodak Pony looks to me like you have used no side or front lighting. What were you using for light? Is there any chance that there is a problem with flash synch?

Ian C · Feb 8, 2013

It looks like the background illumination significantly overpowers the front lighting in the shot of the camera. With an incident meter I suggest:

A. With the back-illumination off, adjust the front illumination for correct exposure. Then switch off the front lights.

B. Switch on the back illumination only. With the diffuser of the meter close to and aimed at the back-illuminated translucent surface the subject rests on, adjust the backlight until you obtain the front/back light ratio you want.

If you set both front and back lights to the same meter reading, the backlit panel will likely look approximately medium gray in the final photo. Youll probably have to experiment to get the lighting ratio satisfactory to achieve the effect you want.

David Brown · Feb 8, 2013

akfotog said:
... but still can't understand the vast difference while using the same exposure readings.

You used the same exposure readings but different lighting. Ian is on the right track here. The back lighting is your problem. The front of the camera was in shadow.

akfotog · Feb 8, 2013

Thanks for the reply all. My setup was a) for the coin, a black foamcore background with copy stand side lighting, 120mm lens, and #32 ext. tube, f22 at 1.5 sec., and b) for the camera, it was placed on the copy stand's built-in lightbox, with side lighting still on, and ext. tube removed (had to raise the camera height), same exposure reading. I used an incident meter reading from both the coin and camera positions to the camera lens, so the exposure should not have changed drastically. It's a mystery. I could understand a reflective reading being off because of the backlighting, but not an incident reading from the same positions.

RalphLambrecht · Feb 8, 2013

i don't see an obvious problem. it wad a black camera,right; what do you want it to look like?,more detail?;wel,then throw some light on it!

E. von Hoegh · Feb 8, 2013

Without seeing the negative, I can't give any input. Your scans show little detail on the camera, but is there detail on the actual negative? Put the neg. on a light table and look at it with a loupe. If there's detail on the neg, the trouble is in the scan.

akfotog · Feb 8, 2013

Thanks Ralph and E. von Hoegh. The Kodak Pony is 70% chrome and the rest is brown, and the intent was to show the camera on a pure white background. Little detail of the camera on the negative. Will try it again this weekend, time permitting, and increase the lighting (and angles). Thanks again, have a great weekend.

Maris · Feb 8, 2013

E. von Hoegh said:
Without seeing the negative, I can't give any input. Your scans show little detail on the camera, but is there detail on the actual negative? Put the neg. on a light table and look at it with a loupe. If there's detail on the neg, the trouble is in the scan.

Yes, check the negatives themselves. The positive thumbnails aren't what you shot. They are re-worked and inverted digital pictures of what you shot. Scanners are in effect digital cameras operating with their own variable (and mysterious to me) internal protocols for taking an input and turning it into some kind of output.

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